Add possibility to change size and thickness of ram_widget and of brightness_widget

[NicolasWebDev]

Hi,

Right now I can change the size of the volume_widget and of the batteryarc_widget by passing { size = 30, thickness = 3 }, but these parameters are not supported in ram_widget nor in brightness_widget.

I have just changed to a HiDPI display (15.6'' with a resolution of 3456x2160), and the default size for both these widgets appear really small.